Cargo hauling trailers drawn by over the road tractors are equipped with many signaling and safety features. Illuminated signaling lamps include brake lights, turn signals, and running lights. Safety features also include pneumatic braking systems, including primary braking and emergency braking systems. Trailers must be periodically inspected for proper operation of these signaling and braking systems. Breaks in the electrical wiring or in the pneumatic hoses are common problems which arise. Corrosion of electrical connections or of braking system components are also frequently encountered.
One way of testing and observing these systems is to connect a towing vehicle, such as a tractor trailer, to the trailer. A tractor has the voltage and pneumatic sources for operating the systems. An observer can activate the various systems individually, and then observe the results. This method can be quite inefficient, since it relies upon the presence of an unused tractor and also requires time to make connections and carry out the cumbersome processes of manually activating each system, before then walking around the trailer to verify proper performance.
A number of patents concerned with monitoring and testing systems for vehicles, including cargo trailers and attached tractors are known. DiLullo et al., in U.S. Pat. Nos. 4,897,642 and 5,025,253, describe a system and method for remotely monitoring the status and location of multiple part vehicles using satellite communications. In U.S. Pat. No. 5,142,278, Moallemi et al. disclose an apparatus and method for communication between a tractor and trailer via existing truck wiring, and transmitting the status to a remote receiver. Gee et al., in U.S. Pat. Nos. 5,397,924 and 5,693,985, describe a truck tractor and trailer communication system that uses a standard seven pin connector where high speed data communication links are employed for control and diagnostics of the electrical system. In U.S. Pat. No. 5,488,352, Jasper discloses a communications channel that interconnects controllers located in a tractor and a trailer unit. The controllers monitor and control various subsystems of the tractor/trailer combination.
An apparatus and method for performing diagnostic tests on the electrical systems of recreational vehicles is disclosed by Hammerly in U.S. Pat. No. 5,086,277. The device contains switches and LEDs plus a voltmeter and an ammeter for use in testing the circuits. A simple trailer lamp testing and lamp storage apparatus is described by Doland, Sr., et al. in U.S. Pat. No. 5,416,421. Walkington et al., in U.S. Pat. No. 5,604,439, disclose a tractor/trailer lamp circuit continuity test device with LEDs to indicate if the lamps are operating. Gutierrez, in U.S. Pat. No. 5,602,482, discloses a trailer system tester that includes a portable diagnostic device for checking electrical signaling systems for trailers. Also included on the device is a pneumatic system to pressurize the air breaks of the trailer for leak testing. The use of vacuum or hydraulic breaks is also mentioned.
Thus, there is an unmet need for a device that will allow an individual to test both the electrical circuits and the pneumatic braking systems of a cargo trailer, as well as assist the individual in locating trouble spots in any of these systems.